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Marktm
Gold Member
Posts: 560
Joined: Thu Jan 21, 2016 10:49 am
Delivery Date: 09 Jan 2016
Leaf Number: 022737
Location: Houston, TX

Re: Battery Upgrades are very possible

Fri Jun 26, 2020 5:37 am

mux wrote:
Wed Jun 24, 2020 10:20 pm
You're blowing ever so slightly colder air over a battery case with poor thermal conductivity. There's not enough delta-T and not enough thermal conductivity to get much heat out of the battery that way. During a QC session the battery is producing between 1-2.5kW of heat, and the best you can do with 10C colder air is remove in the order of 100W or so. It's going to delay thermal throttling a little bit, but not much.
Did some grosso modo calculations on flat plate cooling using a cold plate directly below the battery case - with heat transfer material between the bottom battery case and the protector plate. BY NO MEANS AN EXACT CALCULATION. However as the film heat transfer coefficients are so low on the three limiting air surfaces, that - as mux points out - the cooling is extremely limited. It appears using a refrigerated cold plate below the battery - say on a garage floor that is 40 degrees Fahrenheit below the battery temp would only cool by a few oF over an entire night. I'm sure blowing air and adding radiation "cooling" to the calcs might add accuracy, but not likely change results - internal cooling is the realistic answer.

I am sure open to alternative proof of something that might work - I have a garage to experiment with and live in a very hot climate!
2012 Leaf SL; 46,000 miles. Battery replaced November 1st, 2016.

coleafrado
Posts: 246
Joined: Fri Oct 11, 2019 11:58 pm

Re: Battery Upgrades are very possible

Mon Jul 13, 2020 5:21 pm

Marktm wrote:
Fri Jun 26, 2020 5:37 am
Did some grosso modo calculations on flat plate cooling using a cold plate directly below the battery case - with heat transfer material between the bottom battery case and the protector plate. BY NO MEANS AN EXACT CALCULATION. However as the film heat transfer coefficients are so low on the three limiting air surfaces, that - as mux points out - the cooling is extremely limited. It appears using a refrigerated cold plate below the battery - say on a garage floor that is 40 degrees Fahrenheit below the battery temp would only cool by a few oF over an entire night. I'm sure blowing air and adding radiation "cooling" to the calcs might add accuracy, but not likely change results - internal cooling is the realistic answer.

I am sure open to alternative proof of something that might work - I have a garage to experiment with and live in a very hot climate!
The steel plate is definitely the limiting factor here. Its k-value is way too high!

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